The present invention relates to an airbag apparatus that protects an occupant from an impact by deploying and inflating an airbag at a position close to the occupant seated in a vehicle seat when an impact due to, for example, a collision is applied to the vehicle.
An airbag apparatus is effective for protecting an occupant from an impact when an impact due to, for example, a collision is applied to an automobile. As one form of the airbag apparatus, for example, Japanese Laid-Open Patent Publication No. 2014-69585 discloses an airbag apparatus including a gas generator and an airbag. The gas generator is elongated and includes a gas outlet portion at one end. The airbag includes an inflation portion that is inflated by inflation gas ejected from the gas outlet portion.
The airbag has a tubular storage chamber for storing the gas generator outside the inflation portion. More specifically, the airbag is configured by a first base fabric sheet. A second base fabric sheet is superposed the first base fabric sheet from the inner side. The first base fabric sheet and the second base fabric sheet are sewn together and an opening is provided in the first base fabric sheet to form a tubular storage chamber with opened opposite ends. The opening in the first base fabric sheet is an insertion port for the gas generator. The gas generator is inserted into the storage chamber through the insertion port.
The airbag further includes a pair of restrictions. The restrictions are formed by sewing the first base fabric sheet and the second base fabric sheet to each other to be located between the insertion port and the gas outlet portion at positions on opposite sides of the gas generator in the radial direction. In the positions where the restrictions are provided, the gap between the inner wall surface of the storage chamber and the gas generator is smaller than in other portions. This limits leakage of inflation gas to the outside from inside the inflation portion through the storage chamber.
However, since a pair of restrictions disclosed in Japanese Laid-Open Patent Publication No. 2014-69585 is formed by sewing the first base fabric sheet and the second base fabric sheet together, the stiffness of the restrictions is increased. The restrictions thus resist deformation along the gas generator. Therefore, there is a limit in reducing the gap between the inner wall surface of the storage chamber and the gas generator at the positions where the restrictions are provided, and there is room for improvement in the sealing performance.